Battery grid casting method and machine



y 15, 1959 c. A. NICHOLS ETAL 3,455,371

BATTERY GRID CASTING METHOD AND MACHINE Original Filed Aug. 14, 1964 4Sheets-Sheet 1 w 12 Il w .92: MENTORS Charles 0. ?2'c)2a)s ATTORNEY y15, 1959 c. A. NICHOLS ETAL 3,455,371

BATTERY GRID CASTING METHOD AND momma 4 sheets-sheet 2 Original FiledAug. 14, 1964 z QQQSQQG fiwsmmmmmm dmsmissm n UQQQQQQQ CEEEEEE UQQQQUQQmsmmsscm QQQQQQQQ QQQQQQQQ n mmmmmimi QQQSQQQ umimmmim QQQQQQQQ QQQSQQQsmimmmi INVENTORS C)2ar)es O. Niche): O/ezander H. Jgyce YiLUUUUhUUClmrles ZJ ardner 10171122222 0. Hakka) ATTORNEY hr 1959 c. A. NICHOLSETAL 3,

BATTERY GRID CASTING METHOD AND MACHINE Original Filed Aug. 14, 1964 v 4Sheets-Sheet 5 M? Ma E MI H H H H I H H I H n I I I TI 10 INVENTORS WC'2Iar2es Q Wz'chds a/ezazm'er ii Jgyce Char) [11 Gardner Zl/[Hiam 0. ffezc'ber ATYORNiY y 15, 1969' c. A. NICHOLS ETAL 3,455,371

BATTERY GRID CASTING METHOD AND MACHINE Original Filed Aug. 14, 1964 4Sheets-Sheet 4 IN VENTORS CVzar/es 0. 771020): 028mm 19 Jgyce C'karks[if ara'ner BY $4M ATTORNEY United States Patent M 3,455,371 BATTERYGRID CASTING METHOD AND MACHINE Charles A. Nichols, Largo, Fla., andAlexander H. Joyce, Detroit, Charles W. Gardner, Oxford, and William A.Fletcher, Bloomfield Hills, Mich., assignors to General MotorsCorporation, Detroit, Mich., a corporation of Delaware Originalapplication Aug. 14, 1964, Ser. No. 389,564. Divided and thisapplication Oct. 21, 1966, Ser. No. 598,572

Int. Cl. B2211 11/06 US. Cl. 16487 7 Claims ABSTRACT OF THE DISCLOSUREIn a preferred form, a method for continuously casting battery grids byrotating a drum mold with respect to a continuous belt pulley system. Anopen-ended throat region is formed in cooperation with adispenser headand the periphery of the rotary drum mold when it first meets thecontinuous belt. The method includes the circulation of molten metalinto the throat region at a rate in excess of the volume of the moldcavities exposed to the throat region so as to maintain a flow velocityin the throat region across the mold cavities to prevent premature metalsolidification. The belt is uniformly pressed against the outerperiphery of the mold to wipe less than the full amount of the flow intothe throat region into the mold cavities and the excess flows out theopen ends of the throat region. A layer of low heat diffusivity materialis maintained at the surface of the mold to further prevent prematuresolidification of the molten metal as it flows into the mold cavities.

This application is a division of application Ser. No. 389,564, filedAug. 14, 1964, now US. Patent No. 3,300,- 821, issued Jan. 31, 1967.

This invention relates to an improved machine and method forcontinuously casting strips of battery grids from molten material.

While machines for continuously manufacturing strips of material orcastings from a molten mass are known, none of these machines or methodshas been completely suitable for casting articles having close tolerancecomponents or small dimension, for example, a battery grid having gridwires directed between crossbars enclosed by a rim or peripheral bead onthe outer periphery of the grid. In casting articles of this type by acontinuous process, it has been found that presently known machines areunable to completely assure good reproduction of the mold configurationbecause of problems in completely filling the mold and extracting thecasting therefrom.

Accordingly, an object of the present invention is to provide animproved method for manufacturing continuous strip castings including ahigh-low principle of molding wherein a first portion of the mold ismade of a material having a low diffusivity factor for preventingsolidification of molten material before the mold has been completelyfilled and a second portion of a high diffusivity factor for reducingthe surface tension of the molten material to assure accuratereproduction of the mold contour in the fine detailed portions thereof.

A further object of the present invention is to improve machines forcontinuously manufacturing castings as a continuous strip from a mass ofmolten material of the type including a rotary drum mold, a dispenser,and a belt by the provision of improved means for locating the dispenserin close tolerance relationship with the mold and a floating roll thatcompensates for drum eccentricity to Patented July 15, 1969 maintain asubstantially constant geometry between roll and mold as molten materialflows from the dispenser into the juncture between the mold and rollwhereby an even distribution of molten material into the mold isobtained while preventing flashing across the mold face to assurecomplete reproduction of the mold contour.

A further object of the present invention is to improve the manufactureof battery grids or the like in machines of the above-described type byan improved continuously flowing stream of molten material to and from apool for filling a continuously advancing mold surface.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein preferred embodiments of the present invention areclearly shown.

In the drawings:

FIGURE 1 is a diagrammatic view of a process line including thecontinuous casting machine and method of the present invention;

FIGURE 2 is a view in side elevation of the present invention;

FIGURE 3 is a fragmentary view partially in side elevation and insection showing the dispenser, floating roll, drum mold and beltrelationship in the improved machine;

FIGURE 4 is a plan view looking in the direction of arrows 44 in FIGURE2;

FIGURE 5 is a reduced view in vertical section taken substantially alongthe line 5-5 of FIGURE 3 including a showing of means for raising andlowering the dispenser;

FIGURE 6 is a fragmentary, enlarged view in vertical section taken alongthe line 66 of FIGURE 2;

FIGURE 7 is an enlarged, fragmentary view in vertical section of afurther embodiment of a drum mold surface; and

FIGURE 8 is an enlarged, fragmentary view in vertical section of anotherembodiment of a mold of the present invention.

Referring now to FIGURE 1 of the present invention, a process line forcontinuously manufacturing strip castings, for example, castings ofbattery grids or the like, is illustrated as comprising a melting system10 for directing molten material, for example, an antimony lead alloy toa casting machine 12 and thence through a trim station 14 for trimmingthe casting and thence through a paste station 16 for filling the voidsin the battery grid castings with a suitable electrochemically activematerial, and thence through a shear station 18 for separating thecontinuous strip of battery grids into individual units. These units arethen passed through a suitable oven 20 for curing the active material inthe grid framework and thence to a secondary shear station 22 forfurther separating the finally cured battery grids into battery sizeunits which are then carried to a suitable assembling station by meansof a conveyor belt 24.

The continuous grid casting machine 12 is best illustrated in FIGURE 2as comprising a large diameter mold drum 26 having an outer peripheralflange portion 28 supported by a radially inwardly directed web or disc30 supportingly received on a drum adapter unit or element 3.2 having aplate portion 34 secured to the web 30 by suitable fastening means, suchas a key. In the illustrated embodiment, a key element (not shown) islocated in engagement between the web 30 and plate 34 to preventrelative movement between the drum 26 and the adapter unit. A shaft 40secured to the adapter is rotatably supported upon suitable fixedframework 42 whereby the mold drum 26 is rotated about the axis of shaft40 by suitable drive means (not shown) acting through shaft 40. Theouter periphery of the mold drum 26 will thus drivingly engage acontinuous belt 44 that passes about a pulley 45 rotatably supported onthe fixed support 42 by means of a shaft 46 and thence across a belttension roller 48 rotatably supported on a movable plate 50 that isbiased so as to produce a predetermined pressure between roller 48 andbelt 44 by a spring loading device 52 including a threaded stud 53received by a fixed bracket 54- for adjusted movement therein so as tovary the spring force of a coil spring 55 in surrounding relationshipwith one end of stud 53. Following passage over the belt tension roller48, belt 44 passes over spaced rollers 56, 58 located thereabove toguide the belt 44 in a substantially vertical direction prior to itspassage over an equalizing roller 60. As best seen in FIGURES 2 and 5the roller 66 is supported at each of its ends on one end of each of apair of equalizing arms 62 each having a downwardly curving upperportion 63 thereof pivotally supported on a pin 64 supported by thefixed support 42. The opposite end or offset portion 65 on each arm 62depends substantially in a vertical plane and supports suitablecounterweights 66 that tend to pivot the roller 60 about the axis of pin64 toward the outer periphery of the drum 26 where the belt 44cooperates with drum 26 to form a throat region 68 therebetween as itpasses from the roller 60 onto the drum 26.

The continuous belt 44 then passes about the drum 26 through less than180 of the outer circumference thereof to return to the idler pulley 45from whence the continuously cast grid strip is directed to a furtherprocessing step, for example, to the trip stage 14 illustrated in FIG-URE 1. In order to produce the continuous strip of casting from a sourceof molten material, the belt 44 is preferably constructed of a hightemperature resistant material of substantial flexibility, for example,a special silicone rubber, 4-ply belt with a No. 8025 fabric material asmanufactured by Goodyear Tire and Rubber Company. This material was usedon one Working emodiment of the machine and in addition to havingdesired thermal durability, it had an outer surface of approximatelysixty durometers in order to produce castings of good quality.

Previous to the present invention, it was recognized that continuousstrips might be continuously cast from amass of molten material;however, previous machines are limited to casting articles wherein thecomponent parts thereof have substantial dimensions without closetolerances. When the mold configurations of previous machines aremodified to include small dimensional characteristics and fine detailedportions that must be continuously manufactured to very closetolerances, it has been found that portions of the mold fail to filland, hence, there is not a reliable continuous reproducibility of moldconfigurations and/or there is an overfilling of the mold with aconsiderable flashing of excess material across the mold surface thatrenders the finished casting completely unsuitable for its intendedpurpose.

In the illustrated embodiment of the invention, a molten material is fedinto the throat region 68 between belt 44 and drum 26 in a manner andunder a temperature control that assures that a continuous strip ofsubstantially identical castings of desirable tolerance will be directedfrom the drum 26.

In accordance with certain of the principles of the present invention,improved means are included in the illustrated casting machine 12 touniformly direct a predetermined amount of molten material at a desiredfluidity into a mold cavity on the drum 26 that is representativelyillustrated in FIGURE 4 as including a battery grid 70 having smallcross-sectioned grid wire depressions 72 extending between largercross-sectioned crossarm depressions 74 each being connected at theouter ends thereof to a relatively large cross-section rim depression 76having a tab portion 78 integrally formed therewith.

More particularly, in the illustrated embodiment of the presentinvention, as best seen in FIGURE 3, the

equalizing roller 69 cooperates with the belt 44 in the vicinity of thethroat region 68 to fulfill three important functions in maintaining athroat region of constant geometry. One of these functions is that thetwo independent pivoted equalizing arms 62 and self-aligning bearings atthe ends of the shaft or roller 68 allow the equalizing roller 60 toshift relative to the outer periphery of the drum 26 to compensate foreccentricity or wobble therein.

Furthermore, by adjusting the counterweights 66, it is possible to applyequal force to each end of the equalizing roller 66 whereby a uniformcontact pressure between the belt 44 and the drum 26 is attained acrossthe entire width of the throat region 68. By virtue of the equalizingroller system, any variation in the diameter of the drum due to thermalexpansion is compensated for by pivotal movement of the roller 60 aroundthe pin 64 by an amount equivalent to the thermal expansion in drum 26whereby the contact pressure between the belt 44 and drum 26 ismaintained substantially constant.

By virtue of the above-described characteristics of the equalizingroller system, the throat region 68 is maintained substantiallygeometrically constant and, accordingly, molten material directedtherein can be controlled to produce aclosely controlled filling of thecontinuous mold on the outer periphery of drum 26. In the illustratedembodiment of the invention, as best seen in FIGURES 1-3, moltenmaterial is fed into the throat region 68 from the source 10 of moltenmaterial that is representatively illustrated as including a lead pot 86having a predetermined charge of molten material therein that iscirculated by a pump 82 through a discharge conduit 84 connected to athree-way control valve 86 that directs the molten material through aconduit 88 connected thereto that has one end thereof connected to afitting 90 serving as a support for a thermocouple unit in a thermowell167 thereon. From valve 86 a recirculating conduit 94 directs fluid fromdischarge conduit 84 in by-passed relationship to the dispenser assembly92 during certain phases of the operation of the illustrated castingmachine 12.

The dispenser assembly 92 is connected to the fitting 99 by a line 96through a centrally located inlet opening 98 on the rear face of awedge-shaped head portion 100. Interiorly of the wedge-shaped headportion 100 is a centrally located downwardly directed opening 104 thatdirects molten fluid to a narrow tip portion 106 of head 100 thatoverlies the juncture between the belt 44 and mold drum 26. When thethreeway valve is conditioned to direct molten fluid from the dischargeconduit 84 to the fitting 90, a continuous flow of molten material isdirected through the distributor opening 104 into the throat region 68where the belt and drum serve to divide the molten stream issuing fromthe distributor opening 104 into substantially equal divided streamsthat pass transversely across the face of the continuously advancingmold 70 on the outer periphery of the drum 26 through substantially halfthe Width of the advancing mold.

As the stream of continuous molten material passes across such equalportions on the face of the advancing mold, the belt 44 is continuouslyacted upon by the equalizing roller 60 to wipe a predetermined portionof the continuously circulating molten material into the cavities of theadvancing mold with a continuously uniform pressure across the width ofthe mold suflicient to assure that the molten material will fill evenrelatively small dimensional portions of the mold cavity, for example,the small wire portions 72 therein. As best seen in FIGURE 5, any matterin excess of that required to fill the cavity portions of thecontinuously advancing mold flows exteriorly of the side edges of theouter periphery of the belt 44 and drum 26 where it is received byfunnels 108, 119 located on either side thereof with each of the funnels168, 110 communicating with a like conduit 112 serving to return theexcessive material or overflow to the lead pot 80 for recirculation backto the dispenser assembly 92.

Another feature of the present invention is the fact that theillustrated dispenser assembly 92 serves to prevent leakage of themolten material exteriorly of the throat region 68 other than throughthe open sides thereof into the funnels 108, 110. In order to assureagainst leakage other than through such side openings, the wedge-shapedhead 100 is carefully spotted between the continuous belt 44 and theother periphery of the drum 26 so that a rear surface 114 thereon havinga curvature corresponding substantially to that of the equalizing roller160 serves to slidably direct the belt 44 into a tangential relationshipwith the outer surface of drum 26 and prevent leakage rearwardly of thethroat region 68. A front surface 116 on head 100 having a curvaturesubstantially corresponding to that of the outer periphery of drum 26serves as a front locator against the drum and to seal between the frontof dispenser assembly 92 and drum 26. A desired location of thewedge-shaped head 100, belt 44 and drum 26 is obtained in theillustrated embodiment of the invention by two toggle mechanisms 118,120 for adjusting the wedge-shaped head both vertically and horizontallywith respect to the throat region 68. The toggles 118, 120 are eachconventional arrangements that perform the dual functions of following apredetermined adjusting motion to a locked position. In the illustratedarrangement these toggles serve as a means for obtaining a roughlocation of head 100 with respect to drum 26 and belt 44. Fineadjustment of head 100 is obtained by adjustment means including a flatplate portion 130 supported by suitable means on the fixed framework 42.The plate 130 threadably supports a pair of spaced screws 132, 134 thatdepend therefrom through elongated members or guide sleeves 136, 138respectively. Each of the screws 132, 134 has a bifurcated end 139thereon that is pivotally connected to a lug 140 on the side of the head100 by a pin 141. Each of the screws 132, 134 also has a spring 142located therearound held between a depending part on the plate 130 andthe members 136, 138 to bias the Wedge-shaped head 100 away from theplate 130 to produce a desired vertical spacing of the tip 106 withinthe throat region 68. A continuous chain 150 rides over sprockets 160,162 secured to the upper end of each screw 132, 134, respectively,whereby, upon adjustment of one of the screws, the chain 150 andsprockets 160, 162 conjointly move and the screws 132, 134 are closelyadjusted equally in the vertical with respect to the flat plate portion130 for changing the relationship between head 100, belt 44 and drum 26.

Accordingly, the dispenser head 100 can be closely adjusted to itsoperating position where it is spotted within the throat region 68 sothat the concave rearward surface 114 and the forward surface 116thereon will be in juxtaposition with the belt 44 and drum 26,respectively. By virtue of the above-described adjusting mechanism, whenit is desired to move the dispenser 92 exteriorly of the throat region68, it is merely necessary to release the toggle mechanisms 118, 120.

During the casting of molten material into the molds on drum 26,temperature control of various portions of the device are fairlycrictical. For example, if the temperature is too high at the dispenser,molten lead or the like may fountain up between the interface betweendispenser head 100, belt 44 and drum 26 or if the temperature is toolow, the molten material may tend to solidify in the dispenser torestrict the continuous circulation of molten material transversely ofthe continuously advancing mold face. One representative thermal controlarrangement includes thermal couple controlled cartridge heaters 164having 400 watts at 115 volts located within openings 166 on either sideof the head 100. These heaters, under the control of thermocouples inthermowells 167, maintain the material at approximately 600 F. when theinitial temperature in the pot 80 is around 830 F. Under thesecircumstances, the drum 26 is preferably controlled at about 280 F.During casting of grids within the mold on the outer periphery of drum26, the web 30 of the drum is cooled to prevent the drum temperaturefrom rising above the desired control range. In the illustratedembodiment of the invention, as shown in FIGURE 6, cooling isaccomplished by spraying the web 30 with water from a spray gunapparatus 168. The spray is controlled by a control pyrometer assembly170 that measures the temperature of the inside surface of the drumthrough a surface mirror 172 that reflects.

It has been found that in some cases when the temperature control wasmaintained solely on the drum 26, the grid surface cast. against thebelt 44 had a course grained structure. Accordingly, in certain cases,it may be desirable to also control the temperature of the belt by meanssimilar to that used on the drum to obtain desired grain sizecharacteristics on the belt side of the grids.

The continuous flow of molten material through the throat region 68desirably takes place within a throat region having a maximum volumewith a minimum area of contact with the drum and belt to assure that thebelt will form relatively flash-free accurate grids on the outerperiphery of drum 26. In order to obtain maximum volume with a minimumarea of contact, the throat should have a cross section as close as isfeasible to an equilateral triangle. In addition to the geometricconfiguration of the throat area, other aspects of the invention assurethat lead will completely fill the mold cavities and that excess moltenmaterial will return to the melting pot for reheating. Among theseadditional factors are: (l) a large excess of lead is directed by thepump 82 through the throat region to produce a sutficiently highvelocity to prevent the circulating stream from solidifying; (2) thebelt is constructed from a low-heat conductive material to minimize thetemperature drop of the lead stream in the throat region; (3) the molddrum is hard coat anodized at the outer surface or mold area in rim 28.Such an anodized coat has a low diffusivity of heat that minimizes thetemperature drop of the lead stream on initial contact with the drum. Inthe illustrated machine the anodized coat is a .OO35-.004" insulationlayer that has been sprayed with a very thin layer of a suitablebreak-in compound.

For purposes of this specification, diffusivity refers to thermalconductivity divided by volumetric heat capacity.

Once a portion of the fluid lead stream has been wiped into the moldcavities by the belt 44 and the excess has flowed through the sideopenings into funnels 108, 110, the belt is driven along with the drum26 to trap the molten material in the mold cavities for a predeterminedperiod of time that enables the drum web 30 which has a high heatdiffusivity and is constructed, for example, of aluminum to quench thegrids while maintaining as uniform a temperature as possible across themold surface by controlled heating thereof through a like pair ofburners 174, 176 located in proximity to the drum 26 on either sidethereof. The burners serve primarily to preheat the drum 26 to thedesired drum casting temperature at which time the circulating leadstream will maintain the temperature of the drum under control of thecooling spray gun 168. A third burner pair 177 impinges on the returnlines 112 to prevent solidification of the molten material there-Another aspect of starting the illustrated machine 15 that duringinitial startup, there might be a tendency for excessive flash to formon the surface of the drum. Accordingly, a skiver apparatus 178 issupported over plate 130 above drum 26 so that a blade portion 180' islocated tangent to the diameter of the outer drum with the leading edgethereof closely adjacent on the vertical center line of the drum. Theskiver apparatus includes suitable means for adjusting the leading edgeof blade 180 so that it will not cut into the surface of the drum whileremoving excessive flash from the outer periphery thereof.

In summary, the improved method for continuously casting strips ofarticles having close dimensional tolerances is made possible by passinga continuous stream of molten material tangentially to a continuouslyadvancing rotary mold surface while wiping a predetermined portion ofthe continuously circulating stream into the mold cavity withoutmaterially reducing the temperature of the molten fluid stream below adesired temperature so as to maintain a desired fluidity. One workingembodiment of a machine of the type discussed above successfullycontinuously casts battery grids from a lead alloy containing between 4%and 7% antimonial lead where the variations in liquid temperatureproduced by the differences in antimony in the alloy are compensated forby suitable changes in the drum temperature and temperature of the leadsupply in pot 80.

The method also contemplates the application of a uniform pressure uponthe continuously circulated stream of molten material as it is beingwiped into the rotary mold. For example, in the above illustratedmachine, the equalizing roller produces the desired substantiallyconstant pressure across the mold surface for wiping the desired portionof the stream of material therein. The fact that the belt and outersurface of the drum are of low conductivity material combines with theheating of the pool within throat region 68 to maintain the desiredfluidity of the material as it is initially being cast into place. Thefact that an excessive amount of material is circulated aids inmaintaining a desired fluidity because the fluid stream passes at arelatively high velocity across the throat region during the castingprocess.

Furthermore, in the illustrated machine the method of quickly quenchingthe mold is carried out by the fact that the drum interior serves as asubstantial heat sink of high-heat conductivity material closelyadjacent the low-heat conductivity mold cavities of low diffusivity. Therelationship of high and low heat diffusivity regions can be referred toas a high-low theory of casting. By virtue of this theory, it has beenfound that the final castings are uniformly quenched across the moldface in a relatively short period of time. Accordingly, the belt onlyhas to pass over a portion of the drum less than 180 and because of thereduced contact between the drum and the continuous belt, the belt hasimproved wear characteristics.

By virtue of the above-described apparatus the casting rate can beincreased or decreased by merely varying the cooling action of spray gun168 to take care of the variation of heat input into the drum 26produced by the operation thereof at changing speeds. Furthermore,variations in grid thickness can be easily compensated for in theillustrated machine by increasing lead supply and water flow to thespray gun to compensate for the added heat input into the systemproduced by the increased grid thickness. Like reductions in lead supplyand cooling water flow will occur for castings having smallerthicknesses.

In accordance with other concepts of the present invention, in certaincases the mold shape might be such that it is difficult to overcome thesurface tension of the molten material being wiped therein by belt 44.In this case, the mold cavity has been modified to the form bestillustrated in FIGURE 7 to have a layer 182 of low-thermal conductivitymaterial that is substantially greater in thickness than the anodizedsurface discussed above but still of low diffusivity. Furthermore, thelowconductivity surface does not overlie all portions of the grid moldcavity. For example, in FIGURE '7, the lowconductivity material is suchthat the material being wiped from the throat area 68 into the outerperiphery of the drum 26 is chilled at the base of depressions 72', 74'and 76 corresponding to like depressions in FIG- URE 4. The drum 184 inthis embodiment is of a highconductivity material such as aluminumhaving high diffusivity that will rapidly chill the molten material inthe bottom of the mold depressions while the remainder of the castingconfiguration is maintained at a higher temperature because of thelow-heat diffusivity properties of the insulating layer 182. Because ofthis modified highlow principle of casting, it has been found that thesurface tension of the molten material is substantially overcome so thatthe molten material will substantially completely fill all portions ofthe grooves of the mold to assure accurate mold reproduction. The smallarea of the mold that has the high-heat conductivity characteristicswill not substantially raise the overall heat transfer from the pool inthe vicinity of throat 68 sufficiently to make material solidification aproblem prior to complete filling of the mold. This high-low principleof casting has been carried out by using a rubber insulating coat withit being understood that other suitable insulators, for example,synthetics such as epoxy resins and the like would be equally suited forpracticing this aspect of the invention.

In the embodiment of FIGURE 8, the high-low principle is carried out byforming an insulating layer 186 on the outer surface of a lug 188 thatis bolted to the outer rim 190 of a rotary drum 192. In this embodimentdepressions like those in FIGURES 26 and FIGURE 7 are formed in thelayer 186 and each lug is sealed at its end by a seal insert 194 thatextends transversely across the full width of the rim 190.

While the embodiments of the apparatus of the present invention asherein disclosed constitute preferred forms, it is to be understood thatother forms might be adopted and furthermore, it is understood that themethod may be practiced by apparatus other than that illustrated.

What is claimed is as follows:

1. A continuous casting method comprising the steps of, forming an openended throat region between a rotary drum having cavities in its faceand a continuous belt for closing the cavities, continuously exposing alimited extent of the cavities to the throat region by rotating thedrum, pumping a predetermined amount of molten material into the throatregion in excess of the volume of the cavities exposed to the throatregion, wi ping a part of the predetermined amount of molten materialinto the cavities in the face of the rotary drum, diverting the excessmolten material through the throat region end openings to maintain aflow velocity throughout the throat region to prevent metalsolidification in the throat region, trapping the molten material wipedinto the mold cavities for a predetermined period of time until thematerial solidifies therein, and removing the solidified material fromthe mold cavities.

2. In the method of claim 1, said pumping of molten material into thethroat region including directing the molten material into a centralpart of the throat region to cause velocity fiow transversely of theface of the rotary mold in substantially equal divided quantities fromthe central part of the throat region to the throat end openingsthroughout the width of the face of the drum.

3. In the method of claim 1, said wiping including application of auniform and constant pressure against the belt along an axis across thewidth of the belt by pivotally supporting the belt at its contact withthe drum surface for free pivotal movement toward and away from therotary drum.

4. The combination of claim 1, including the further step of controllingthe drum temperature by sensing the inside surface temperature of thedrum and spraying the drum with cooling water in accordance with thesensed temperature.

5. A method for continuously casting battery grids in mold cavities on arotary drum comprising the steps of engaging a continuous belt with asegment of the rotating drum through less than of the outercircumference of the drum, locating a dispensing head immediately abovethe initial point of engagement between the belt and drum to form anopen-ended throat region for the flow of molten metal into the moldcavities and for the escape of excessive molten metal from the sides ofthe dispensing head, directing molten metal at a predetermined flow rateinto the throat region to cause filling of the mold cavities and flowthrough the open ends of the throat region, applying a continuouslyuniform pressure across the width of the belt to cause the belt touniformly press the molten metal in the throat region into the moldcavities, and conjointly controlling heat input to the metal in thethroat region and heat loss from the drum to prevent the molten materialfrom escaping at interfaces between the dispensing head and the rotarydrum while preventing solidification of the molten material prior tofilling the mold cavities.

6. In the method of claim 5, said conjoint controlling including sensingthe temperature of the metal in the throat region and directing heatenergy to the dispenser for heating molten metal as it enters the throatregion, said conjoint controlling further including sensing the insidesurface temperature of the drum and spraying the drum with cooling waterin accordance with the sensed temperature.

7. In the method of claim 5, limiting thermal heat transfer from thethroat region by providing a layer of low heat diffusivity on the drumto reduce heat flow from the cavities therein while the cavities passthrough the throat region.

References Cited UNITED STATES PATENTS 521,791 6/1894 Griscom 164-276883,312 3/1908 Holley l64278 1,220,211 3/1917 Feldcamp et a1. 164-2781,612,737 12/1926 Lane 164278 1,651,678 12/1927 Davis 164278 2,206,9307/ 1940 Webster 164-278 X 15 J. SPENCER OVERHOLSER, Primary Examiner R.S. ANNEAR, Assistant Examiner

